Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Mar 27, 2015; 7(3): 289-303
Published online Mar 27, 2015. doi: 10.4254/wjh.v7.i3.289
Genotypes and viral variants in chronic hepatitis B: A review of epidemiology and clinical relevance
Catherine MN Croagh, Paul V Desmond, Sally J Bell
Catherine MN Croagh, Paul V Desmond, Sally J Bell, Department of Gastroenterology, St Vincent’s Hospital, Fitzroy, Victoria 3065, Australia
Author contributions: Croagh CMN wrote the paper; Desmond PV and Bell SJ reviewed and added revisions to the manuscript.
Conflict-of-interest: None.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Dr. Catherine MN Croagh, Department of Gastroenterology, St Vincent’s Hospital, Level 4, Daly Wing, 35 Victoria Parade, Fitzroy, Victoria 3065, Australia.
Telephone: +61-3-92883580 Fax:+61-3-92883590
Received: September 15, 2014
Peer-review started: September 20, 2014
First decision: November 14, 2014
Revised: December 4, 2014
Accepted: December 29, 2014
Article in press: December 29, 2014
Published online: March 27, 2015

The Hepatitis B Virus (HBV) has a worldwide distribution and is endemic in many populations. It is constantly evolving and 10 genotypic strains have been identified with varying prevalences in different geographic regions. Numerous stable mutations in the core gene and in the surface gene of the HBV have also been identified in untreated HBV populations. The genotypes and viral variants have been associated with certain clinical features of HBV related liver disease and Hepatocellular carcinoma. For example Genotype C is associated with later hepatitis B e antigen (HBeAg) seroconversion, and more advanced liver disease. Genotype A is associated with a greater risk of progression to chronicity in adult acquired HBV infections. Genotype D is particularly associated with the precore mutation and HBeAg negative chronic hepatitis B (CHB). The genotypes prevalent in parts of West Africa, Central and South America, E, F and H respectively, are less well studied. Viral variants especially the Basal Core Promotor mutation is associated with increased risk of fibrosis and cancer of the liver. Although not currently part of routine clinical care, evaluation of genotype and viral variants may provide useful adjunctive information in predicting risk about liver related morbidity in patients with CHB.

Keywords: Chronic hepatitis B, Genotype, Pre-core, Basal core promotor, Mutations

Core tip: Chronic hepatitis B (CHB) is a major global cause of liver related morbidity and mortality. Genotypes of the Hepatitis B virus have distinct geographical distributions and are known to influence a number of clinical features of disease and response to treatment. Certain well recognised viral mutations are also known to influence clinical risk of cirrhosis and hepatocellular carcinoma but in addition may have implications for vaccination programs and screening of blood for donation. This review examines the current state of knowledge about genotype and viral variants of CHB and their utility in the management of this disease.